The invention relates generally to propellers for UAVs (unmanned aerial vehicles) and more particularly to collapsible propellers.
Collapsible, or folding, propellers are known in the prior art. Most commonly, prior art folding propellers use a single mechanical hinge close to the yoke of the propeller to deploy each blade. As shown in FIGS. 1A and 1B, a prior art folding propeller 10 includes one or more blades 12, each attached to a central yoke 16 by means of a hinge 14. Central yoke 16 is attached to shaft (not shown) which connects to a motor for causing rotation of propeller 10. FIG. 1A shows propeller 10 in a folded configuration, while FIG. 1B shows propeller 10 in an opened configuration.
Single hinge 14 in each blade 12 does not allow blade 12 to completely conform to the surface upon which it is stowed. Depending on the application, the stowed surface may have a variety of forms, including the nose of an aircraft, for example. Because of the required twist in the blade, an aerodynamically-designed blade is not flat, and a single hinge does not permit the blade to follow an arbitrary curvature. Additionally, the diameter of the yoke used in prior art folding propellers represents lost propeller disk area, and this can be significant if hinging at larger radii is required.
Thus, a need exists for more flexibility and better shape conformity in folding propellers. A need further exists for a folding propeller with a smaller central yoke and an improved hinging mechanism.